In the harvesting of fruit and vegetables it is common practice to use relatively large containers throughout the fields or orchards which are filled by pickers or by automatic harvesting machines. The large containers are then moved to a central area where the fruit and vegetables therein are dumped into a washing, sorting, grading, or the like station. It is desirable for such containers to be as large as possible, to the extent of being capable of holding 5,000 lbs. or more of fruit or vegetables. Therefore, it can be seen that the dumping operation requires special equipment to handle such large size containers. While the instant invention is primarily directed to containers for fruits and vegetables, it is apparent that the ensuing description would be equally applicable to any other type of product or material which is loaded in an open top container, the container moved to a dumping station where it is dumped from the container and the container returned to the loading station.
Several problems arise because of the containers being used and the extreme weight involved. Care must be taken to adequately support the container as it is lifted and tilted in order to prevent rupture of the container sides or bottom during the dumping operation. For example, there are presently available lift trucks in which the tynes thereof will slip beneath a container and then rotate 90.degree. or 180.degree. about an axis parallel to the tynes to dump the contents of a container. However, when such rotation occurs, extreme pressure is brought to bear on the points of engagement of the types with the underside of the container. If the container is very heavy and if there is not sufficient reinforcing of the container at the areas of engagement, the container may fail or rupture with undesirable attendant results.
As far as the prior art is concerned one type of container dumping apparatus is illustrated in the Thompson et al U.S. Pat. No. 3,713,554. However, it can be easily seen that this is a specialized piece of equipment, that the device grips at points along the top edge of the container only, that the container itself must be very strong, especially at the upper edges thereof to withstand the forces exerted as the container is tipped, and that the maximum weight capacity of the apparatus is about 1,000 lbs. Further, the apparatus is not itself portable so that the containers have to be moved in from the fields, set down, then picked up by the apparatus disclosed.
Another patent exemplary of a material handling apparatus which is tilted to empty is disclosed in the Keneson et al. U.S. Pat. No. 3,656,643. This patent discloses a material handling box which is picked up between the horizontally spaced tynes of a lift truck and includes tyne or fork engaging members on the sides of the box. When all of the tyne engaging members (16,18,20) are engaged by the tynes the container is carried in an upright position. However, when the tynes are moved slightly rearwardly to clear the front members 16, the container will be caused to tilt to a dumping position. Obviously this type of apparatus is extremely limited in capacity because it must be narrower in width than the space between the tynes of the fork lift truck. Further, it is extremely important to note that the container can only be shifted on the tynes for tilting from a rest position. Therefore it could not be lifted and caused to tilt from an elevated position as would be necessary when lifting a container over the side of a wall or other impediment to dump the articles down on the other side.